The present invention relates in general to a method for classifying the source of insulation and, in particular, to a method for determining the source of expanded vermiculite insulation used in attics and walls.
There are approximately 1 million homes in the United States that have expanded vermiculite attic insulation (U.S. EPA, 1985). Prior to 1990, there were four sources that produced most of the vermiculite ore used for attic insulation. Three of these are located in the United States in Enoree, S.C.; Louisa, Va.; and Libby, Mont. The fourth is located in Palabora, South Africa. Most of the vermiculite used for attic insulation originated from the Rainy Creek Igneous Complex near Libby, Mont., where fibrous amphiboles were a common mineral contaminant. Ore from the Libby mine supplied up to 80% of the world's vermiculite. The Libby mine closed in 1990.
Over the last decade, health studies in the town of Libby (Peipins et al., 2003; McDonald et al., 2004) and at expansion plants throughout the United States that processed ore from this location revealed a high rate of asbestos-related lung disease among people exposed to the fibrous amphibole potentially contained in the vermiculite insulation. Vermiculite from other commercial sources in the United States and South Africa apparently do not contain fibrous amphibole in significant quantities. There will be a growing demand for vermiculite insulation inspections and source identification as the public becomes aware of the potential health issues posed by exposure to fibrous amphiboles during home improvements or maintenance in areas insulated with vermiculite ore from the Libby mine, or of the liabilities of owning property containing this vermiculite.